Glass bending mold



Patented 28, 1941 't UNITED STATES. PATENT oFFicE l 2.2611333y l GLASS BENDING MOLD original application May 29, 1937, 'serial No.

145,412, now Patent No. 2,137,115, dated November 15, 1938.

Divided and this application June 28, 1938, Serial No. 216,257

8 Claims.

The invention relates to a mold for use in the bending of'glass sheets, the present application constituting a division of my application, Serial No. 145,412, filedV May 29, 1937, now Patent No. 2,137,115, dated Nov. 15, 1938. 'I'he mold is preferably used in connection with a tunnel kiln, as s'et forth in saidapplication, but

might be used with other types of kiln, if desired. i

In accordance Iwith the preferred practice, the molds are mounted' on carsand carried through a kiln of progressively increasing temperature to bring the glass sheets carried thereby to a temperature at which they'are bent by gravity and settle into the molds. In a further travel through the kiln, the temperature is reduced to a point somewhat below the critical annealing range, at which'time, the glass has set,

permitting the removal of the sheets from the molds. sand of the mold beneath the bent sheets, such sheets are now removed from the molds and transferred toa cooling tunnel through which they are carried and reduced in temperature to a point at which they may be handled. The

cars with the molds thereon are returned, after the removal of the glass sheets, to their starting position to repeat the cycle. l The molds are made ready for reuse by returning the lifting` members to their original positions and smoothing over the sand above the members. 'Ihe mold is illustrated and described as bending a single sheet of glass, but if desired, two sheets,

in bent position.

g The container portion of the mold comprises the metal bottom plate 3, the side plates 4, I,

and the end plates 5 also of metal. The bottom plate 3 also preferably carries a layer of asbestos 6, which acts as a. seal between the bottom plate and the plates 4 and 5. The containercarries mold material 1, which is ordinarily a body of sand mixed with finely divided nre clay of such consistency that the mol will maintain its contour after being shaped so that the surfacev has the desired curvature.V This curvature may be oi various shapes depending upon requirements By lifting members embedded in the' and several plates may be bent in the same mold if the size is small.- Themeans employed to securethe desired contour in sand molds are the same as those heretofore employed inthe art, templates being used to smooth of! the sand to the desired shape.

The edges of the glass sheet 8 to be bent are preferably supported, as indicated in Fig. l. The metal strip 9 is embedded in .the sand along each side of the mold and carries a strip of asbestos I0 on which is a second metal strip Il, which carries a strip of asbestos I2. In the bending operation, the edges of the glass sheet' move inward and the partsll and I2 slide with them on the surface of the strips I0 until the sheet is well settled in the mold, at which time the strips II and I2 are removed from' the mold by operators working through openings in the side wa'lls `of the tunnel kiln. 'I'he glass iinally reaches theL dotted vline position A, indicated in Fig. l, the bent sheet being shown in full lines in Fig. 2. At a later stage in the operation, when the surface of the mold is being smoothed over for another operation, the metal strips'. 9 act as guides upon which the bars carrying the template may rest in the movement of the template one upon the other, may be bent at one operalongitudinally of the mold. l

Provision is made for lifting the bent sheet from the mold when the car carrying such mold reaches a point in the kiln, where the tempera Vture has dropped to a point somewhat below the critical annealing range, in the form of a pair of metal bars I3, I3 'embedded in the sand and having a length slightly greater than that. of the sheet. -These bars are preferably hollow,

as indicated in Fig. 1, and'of wedge form to facilitate forcing them down through the sand line II-II of Fig. l, but with the glass sheet to the desired position. 'Ihe upperfaces of the bars are preferably provided with layers of asbestos Il, which act as insulation and to prevent any marring of .the glass when the sheet is lifted from .the mold. Each bar is provided at 'its end with a rectangular guide socket I5 and through this socket extends a supporting bar I6 provided with a series of perforations I1. 'I'he sides of the socket I5 are provided with perforations through which a pin I8 extends for locking the member Il to the socket. This permitsthe bars to be used with molds* having dlerent degrees of curvature, sinceA the bars must `set at diiIerent distances from the, bottom of the container, depending upon the curvature of the `face of the mold.' The walls l of the mold are slotted, as indicated at I9, to receive the 'members lIt and sockets Il, such slots serviug/` as guides to maintain the members I 6 in vertical position and in the same relative position at the two sides ofthe container. The ends of the bars I6 are bent, laterally, as indicated at 20, and serve as means for lifting the bars I3 and the glass sheet carried thereby from the mold after the sheet has set and its temperature arrived at a point somewhat below the lower limit of the critical annealing range.

After the bent sheet has been removed from the mold, it is carried through a cooling tunnel. in which its temperature is allowed to drop gradually to the point at which it can be conveniently handled. The mold is prepared for reuse by returning the lifting bars I3 to their original position. as shown in the drawing, the openings in the sand above the bars being restored by the use of a template as heretofore referred to. The mold can now be returned on its car -to the entrance end of the leer and the cycle repeated. This return to theentrance end of the leer can be accomplished without allowing the mold to completely cool oil. so that .a large part of the heat stored in the mold is comprising a metal container, a body of unbonded particles of refractory material in the container having its surface rounded to the contour of the glass sheet to be bent, and 'lifting members embedded in the material of the mold beneath the surface thereof and adapted to pass through the body of unbonded particles and lift the glass sheet from the mold after it has been bent to t the contour of the mold.

2. A mold for use in bending a glass sheet comprising a metal container, a body of unbonded particles of refractory material in the container having its surface rounded to the contour of the glass sheet to be bent, lifting bars embedded in the material of the mold beneath the surface thereof and movable through said body for lifting the bent sheet, and lifting members connected to the bars and extending to the exterior of the mold.

3. A'mold for use in bending a glass sheet comprising a metal container, a body of un-l bonded particles of refractory material in the container having its surface rounded to the contour -of the glass sheet to be bent, lifting bars embedded in the material of the mold beneath 'the surface thereof and movable through said body for lifting the bent sheet, means'resting on the bottom ofthe container for supporting the bars at varying distances from said bottom.

4. A mold for use in bending a glass sheet comprising a metal container, a body of unbonded particles of refractory material in the container having its surface'rounded to the contour of the glass sheet to be bent, lifting bars embedded in the material of lthe lmold beneath the surface thereof and movable through said body for lifting the bent'sheet, and lifting members connected to the bars and extending to the exterior of the mold, said bars being of wedge cross section to facilitate forcing them downward through the molding material.

5. A mold for use in bending a glass sheet comprising a metal container, a body of unbonded particles of refractory material in the container having its surface rounded to the contour of the glass sheet to be-bent,` metal lifting bars embedded in the material of the mold beneath the surface thereof and movable through said body for lifting the bent sheet, a layer of asbestos composition on the upper face of each bar, and lifting members connected to tlfe ends of the bars and extending upward to the exterior of the body of refractory material.

.6i A mold for use in bending a glass sheet comprising a metal container, a body of unbonded particles of refractory material in the container having its surface rounded to the contour of the glass sheet to be bent, lifting members -embedded in and movable through said body to deform the latter and lift the glass therefrom, a ilat metal strip extending longitudinally of the mold on each side of the mold cavity em of asbestos on its upper face.

bedded in the refractory material so that its upper surface is ush with the surface of the material, and a second strip of metal imposed on each of said first strips and having a laye 7. In a glass bending mold, a body of unbonded v particles of refractory material having a molding surface for. molding a sheet of glass at bending temperature, and means normally disposed in the body of material beneath the surface thereof and movable therefrom to deform said body an to carry the glass sheet therefrom.

8. In a glass bending mold, a body of unbonded y 

